1. Field of the Invention
This invention relates to water-soluble, cationic polysaccharides, more particularly, to such polysaccharides, especially quaternary nitrogen-containing cellulose ethers, containing hydrophobic substitution, as well as their utility in aqueous systems and personal care applications.
2. Description of Background Information
Water-soluble, quaternary nitrogen-containing polysaccharides, such as the cellulose ether derivatives described in U.S. Pat. No. 3,472,840 (Stone et al.), are known to possess desirable properties, such as substantivity to many substrates, useful in a variety of applications. Such materials have found utility as flocculants, as pigment retention aids, in paper-making, as anti-static fibers and fabrics, as hand stiffeners for fabrics, in personal care formulations, in adhesives, in printing inks, and so on.
Quaternary nitrogen-containing polysaccharides, such as the cellulose ethers described in Stone et al., are relatively polar compounds due to the presence of the cationic substituents, i.e., the quaternary nitrogen, and absence of lipophilic groups. Such compounds are therefore of limited usefulness in their application to materials and systems which are relatively incompatible with such polar, ionic polymers. In particular, aromatic compounds, such as perfumes, which are lipophilic in character, are not readily retained by such ionic polysaccharides as the quaternary nitrogen-containing cellulose ethers in Stone et al.
Furthermore, cationic polysaccharides, including the cationic quaternary nitrogen-containing cellulose ethers in Stone et al., are sensitive to the presence of other ionic species, such as salts, which are typically found in various applications, such as ionic surfactants used in personal care solutions. The salt sensitivity of ionic polysaccharides has been demonstrated in a variety of ways. Salt addition to aqueous solutions of ionic polysaccharides will generally result in reduced viscosities of such solutions, probably due to interactions between the ionic substituents in the polysaccharide and the ionic species of salt in solution.
U.S. Pat. Nos. 4,228,277 (Landoll I) and 4,243,802 (Landoll II) describe nonionic cellulose ethers which have limited water-solubility. The disclosed nonionic cellulose ethers may contain a level of long-chain alkyl group substitution of from 0.2 wt. % up to a level which renders the cellulose ether either less than 1 wt. % soluble in water or water-insoluble. While some of the disclosed cellulose ethers provide highly viscous aqueous solutions, as well as a relatively high degree of surface activity, they are not substantive, as distinct from cationic polysaccharides in that nonionic polysaccharides do not interact with ionic substrates (such as keratinous material including hair, skin and the like).
European Patent Application Publication No. 109,074 (Massuda) describes polypeptides modified with long-chain tertiary amines to provide a cationic surfactant. The polypeptide is described as a surfactant providing substantivity to hair and skin as well as increased lubricity providing improved combing. Such protein surfactants have relatively low molecular weights, are substantially crystalline as compared with polysaccharides which are film-forming, substantially amorphous, high molecular weight polymers.
Japanese Patent Application Publication No. 82-28003 (Nakamura) pertains to quaternary nitrogen-containing cellulose ethers having benzyl or cinnamyl substituents useful in cosmetic applications. Such cellulose ethers containing benzyl or cinnamyl substituents provide compositions with increased protection from ultraviolet rays while maintaining cosmetic benefits characteristic of such quaternary nitrogen-containing cellulose ethers.
U.S. Pat. No. 4,001,394 (Fogel et al.) pertains to hair care compositions comprising an anionic or amphoteric detergent and a long-chain alkyl substituted, monomeric, quaternary ammonium compound, including saccharinate. It is disclosed that such hair care compositions provide improvements in cleansing activity and conditioning.
There is therefore a need, which has been long-standing since the development of the cationic, quaternary nitrogen-containing cellulose ethers in Stone et al., to provide quaternary nitrogen-containing polysaccharides exhibiting desirable substantivity and other properties significant for personal care applications, combined with enhanced compatibility with nonpolar materials but while retaining significant water-solubility. Such polysaccharides would have widespread utility to applications not heretofore obtained in the prior art.